about religion, a "pagan" conversion could be a bit odd; I know that until 600 AD paganism was relatively widespread in some part of the empire. however, we should not over-represent it. the case of julian was quite rare, in fact; and the same julian conceived paganism with a "christian" eye. he dreamed of a reborn paganism, in which a sort of church would perform the contact with the people with christianity and other eastern religions had. undoubtly mithraism, as i guess you know well :D, played a major role in shaping the military traditions/uses in the late empire. however, christianity was propaganded in military too. we should not forget that the christian god is often referred as deus sabaoth - the god of the armies - and the old-testamental view of mighty, wrath, and outstanding victories had his good reference to appeal military.

for version 7.1 is already in a workprocess the shaping of several new traits - so religions could be better implemented. there will be more or less 25 religions (or sects) a character could be. christian heresies are treated in fact as proper religions, since they pretended to be so, and only accidents prevent them to became the mainstream. for example, before the defeat at adrianople, the arianism was the "official" christian religion.